RF6001_1 RFMD [RF Micro Devices], RF6001_1 Datasheet - Page 50

• Manufacturer Part Number: RF6001_1
• Description: FRACTIONAL-N RF SYNTHESIZER WITH MODULATOR AND DIGITAL IF FILTER
• Manufacturer: RFMD [RF Micro Devices]

RF6001
Part of the POLARIS™ TOTAL RADIO™ Solution
Note that the relationship between frequency error and AFCD is reversed (negative) with high side injection receive mode. The
AFC register will provide fine tuning over a ±203kHz range for both TX bands and high band RX. For low band RX, the AFC reg-
ister will provide fine tuning over a ±101.5kHz tuning range.
AFCD(17:0) is an 18-bit twos complement signed value.
The host/DSP could decide to use the GSM channel number to generate the OFFS value. The base frequency in the RF6001 is
different than that used by the ETSI standard so an offset needs to be added, and the channel number needs to be multiplied
by 40 to obtain the proper multiple of 5kHz (GSM channels are in 200kHz increments). For example, for E-GSM channel num-
ber ‘n’, the OFFS value may be calculated by:
For 892.2MHz, E-GSM channel number 11, we obtain:
Using the above equation for F
Note that 832MHz is 32 times 26MHz and 1664MHz is 64 times 26MHz. This may simplify calculations in the baseband pro-
cessor. These calculations assume a 26MHz reference crystal frequency. The 26MHz reference can be divided by 1, 2, or 4
internally in the RF6001 for use in the PLL, and the frequency calculation will hold. If a different reference crystal frequency is
used, the actual VCO frequency will be calculated by multiplying F
Reference Oscillator Input
A 26MHz system clock provided by crystal oscillator circuitry must be connected directly to the OSCA and OSCB pins. All of the
internal clocks, the OSCO buffered oscillator output, and the gated clock output on LDTO are derived from the reference clock
circuitry. The output of the DAC2 pin is used to fine-tune the crystal oscillator frequency.
The OSCM pin is used to control the input buffer circuitry. When OSCM=0, all input buffer circuitry is turned off. When
OSCM=1, the input buffer circuitry is turned on. OSCM must be held low during power-up.
Instead of a crystal, a 26MHz system clock (TCXO output) can be connected to the OSCA pin through a decoupling capacitor.
This pin possesses a DC voltage of approximately 1.25V. The output of the DAC2 pin is used to fine tune the TCXO frequency.
The figure below illustrates how a TCXO or crystal reference can be connected to the RF6001. Only one of the two options may
be used at one time.
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OFFS
OFFS
F
VCO
000000000000000000to011111111111111111=0(0Hz) to 131071(203.16005kHz)@1.55Hz resolution.
111111111111111111to100000000000000001=-1(-1.55Hz) to -13071(-203.16005kHz) @ 1.55Hz resolution.
=
=
=
0
40n
40 11
+
×
178440 5kHz
+
⎛
⎝
890MHz
-------------------- -
+
5kHz
178000
×
⎞
⎠
7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical
support, contact RFMD at ([phone] or [e-mail].
VCO
=
=
=
178440
, we obtain
40n
892.2MHz
+
178000
VCO
above by F
XTAL
/26MHz.
Rev A3 DS050929